Oakland, Calif. — Across the country, some 400,000 women, mostly immigrants, work in agriculture, toiling in fields, nurseries and packing plants. Such work is backbreaking and low-paying. But for many of these women, it is also a nightmare of sexual violence.

In a 2010 study from the University of California, Santa Cruz, more than 60 percent of the 150 female farmworkers interviewed said they had experienced some form of sexual harassment. In a 2012 report, Human Rights Watch  surveyed 52 female farmworkers; nearly all of them had experienced sexual violence, or knew others who had. One woman told investigators that her workplace was called the “field de calzón,” or “field of panties.” As an Iowa immigrant farmworker told her lawyer, “We thought it was normal in the United States that in order to keep your job, you had to have sex.”

The reasons behind this epidemic aren’t hard to fathom. Fields are vast and sparsely monitored; workers are often alone. It’s particularly bad for immigrant workers: The Department of Labor estimates that about half of farmworkers don’t have legal immigration papers, which makes them especially vulnerable.

So do low wages and competition for jobs: Male farmworkers make an estimated $16,250 a year and female ones $11,250 a year. With depressed wages and so many workers competing for the same job, women are hesitant to complain.

The problem is hardly a secret. Two decades ago the Equal Employment Opportunity Commission, along with California Rural Legal Assistance, a legal service program that promotes the interests of migrant laborers and the rural poor, created a joint project to concentrate on sexual harassment in the fields.

In 2005, the commission won a $994,000 victory for Olivia Tamayo, a worker at one of California’s largest cattle-feeding operations, who was repeatedly raped by her supervisor. “He took advantage because he knew I wasn’t going to say anything,” she told Ms. Magazine. “It was a trauma that followed me everywhere.”

In September, in one of the largest settlements of its kind, the commission won over $17 million for five farmworkers in Florida who had accused their supervisors of rape and harassment. Some 18 similar cases nationally after 2009  have given women farmworkers $4 million.

Yet these cases involve only a tiny percentage of women who work in agriculture. Research shows that harassment and abuse are much more widespread — and case-by-case litigation isn’t enough to change that.

When women do file complaints, investigations can takes months, even years, which can discourage other women from speaking up. And even when a case is won, criminal prosecution of the harasser or rapist rarely follows.

There are several steps we can take to slow this scourge. Education and outreach are critical — not just for women working in the industry, but also for consumers who can put pressure on the industry to crack down. At the same time, employers themselves often don’t know what’s going on in their own fields.

Still, many employers do know — and use threats and intimidation to keep their workers quiet. We need stronger laws against retaliation, and protections for undocumented workers who come forward.

The administrative barriers to complaints must also be addressed. The Equal Employment Opportunity Commission has few offices in rural areas; they’re usually open only when women are working; and the staff often don’t speak Spanish, much less indigenous languages. What’s more, many government agencies require complaints to be filed online. Many farmworkers do not have access to computers. The commission could make filing complaints easier by setting up a 24/7 hotline in multiple languages, with an actual person answering the phone, instead of automated messages.

Criminal prosecution of sexual assault cases needs to increase as well. District attorneys and state prosecutors must step in, making indictments and fining bosses who tolerate harassment. Women will feel safer filing complaints if they know their attackers can’t just walk away. There has been some success along these lines, including a recent conviction in San Benito.

But perhaps the biggest impediment to fighting harassment in the fields is America’s immigration policy itself. Federal regulations forbid legal aid organizations like California Rural Legal Assistance from directly representing undocumented people, and the illegal nature of their work situations makes it difficult for them to come forward. Finding a path toward documentation and legal employment for these women would also empower them to report those who rape and harass them.

Last year, California Rural Legal Assistance settled a $1.3 million case for a farmworker who was assaulted in a raspberry field, and then sent back to work in her bloody and ripped clothes. “It’s the saddest thing that has happened to me in my life — for me it’s like a wound that’s there,” our client said during the sentencing phase of the case. “I just don’t know how I’ll be able to get out of this trauma.”